György Bertalan

Ceramic precursor in flame retardant systems

Boroxo siloxanes were used as a ceramic precursor, combined with an intumescent flame retardant additive system, in polypropylene. Varying the composition and content of the precursor characteristic changes of melt viscosity were detected. Chemical interaction of the additives at the temperature of processing, confirmed using Fourier transformed infrared (FTIR) methods, are related with these rheological changes. Raman microscopic analyses were used to obtain better understanding of the chemical changes of the precursor during flame treatment. Interaction between boroxo siloxane and layered silicate (montmorillonite) nanoparticles was investigated using thermogravimetry.

Elastomer interphase in particle filled polypropylene; structure, formation and mechanical characteristics

34 Introduction 34 Materials and Methods 35 Sample Preparation 37 Results and Discussion 37 References 59 Paper submitted for publication August 1991

Role of pigments in the stability of polyethylene systems

The photodegradation processes of high-density polyethylene (HDPE) films containing either a phthalocyanine-based pigment, or a rutil (TiO 2 )-based pigment, as well as of the unpigmented films stabilised differently were investigated during photo-ageing, applying mechanical, gel content and XPS measurements. The phthalocyanine pigment-containing film showed degradation characteristics (abrupt decrease of elongation at break after short irradiation period, no gel formation, high concentration of oxygen-containg functional groups on the surface) similar to those of the films containing a low amount of stabiliser. The behaviour of the TiO 2 -containing film and that of the unpigmented films containing a higher amount of stabiliser were also similar (slow decrease of elongation at break, increase of gel content, lower amount of oxygen-containing functional groups on the surface). The concentration of oxygen-containing functional groups in samples pigmented with phthalocyanine increased remarkably with increasing processing temperature. The results suggest that the phthalocyanine pigment influences the photostability indirectly, through reduction of the thermal stability of polymer due to the adsorption of the thermal stabiliser by the phthalocyanine pigment. Coating the surface of phthalocyanine with reactive surfactant improved the photostability of the HDPE film.

New reactive additives for interface modification in multicomponent polyolefin systems

New reactive additives were synthesised and used as interface modifiers in different multicomponent polyolefine systems. The synthesis was carried out in computer-controlled reactor by means of Diels-Alder reaction and condensation. These additives are capable of combining the benefits of dispersing and coupling agents. A part of the synthesised reactive surfactants have also synergistic effect in flame retardant systems. Their surface-active character facilitates the reactive compounding. The undesirable transport processes of stabilisers and components of flame-retardants in polyolefine systems could be effectively controlled by interface modification.

Reactive surfactants – new type of additive for multicomponent polymer systems

A new type of interfacial additive has been developed by the authors recently. The molecules of amphiphilic character are capable of forming chemical bonds at both the polar and the apolar sides. These reactive surfactants have been synthesised in a specially designed computer-controlled reactor system. The aim of the development was to combine the advantages of nonreactive surfactants and reactive coupling agents, making possible an in-line reactive interface modification during the compounding process of the polymer system. The characteristics and effects of the synthesised compounds were determined using methods of analytical and colloid chemistry, like Raman microscopy, surface tension, contact angle and rheological measurements.